Dongles?

Originaly, dongles where used as hardware keys for some applications. Those are small devices that connect into the serial, parallel or USB port.
An USB dongle often looks like an USB connector with only a small part, often smaller that your thumb's nail, protuding when inserted.

If you need some dongle to access a given network, it should be given to you when you subscribe to that service.
It probably have some indentification, probably the logo of the service, in your case, the Virgin logo.
In the case of networking/internet dongles, they often, but not always, have an antena.

Electro
December 2015